2018/10/10 (Wednesday)
| Setup: DIB1/3/4 → 3.2 MHz filters 2/3/1 → cable 3/1/2 → gender changer 3/?/2 → HVConn 1/3/2 → HV 1/2 → DCRC55(1)/DCRC50(3) NaI detector: 1.1 kV (for real) → NaI B/C (dynodes terminated) → Ortec 452(Neg input, gain=2.5, shaping = 6 us, output=+10V)/ Ortec 575A(Neg input, gain=5, shaping = 3 us) → x10/x10 attenuator → DCRCX(4) PB/PA DCRC33(2) → kepco 1kV power supply → HV input |
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| status: | Na22 -125V data last night |
| 0850 | Tower/MC/Coldplate = 29.9/30.5/184 mK, Still = 0.0 mW / 1.4±0.1 K / 0.090 mbar, G1/G2 = 119/126 mbar, 1K Pot = 1.59 K / 16 mbar, Turbo on IVC = 0.74 nbar, MB = 33.4% |
| 0850 | Change trigger thresholds on DCRC3pB/C/D to 13/16/15 |
| 0852 | Start 8x2hr Na22 trigger-test series at HV = -125 V with 15% prebias for 5 min, split into 10 min subruns, with CDMS and NaI detectors running and DCRC2 as HV controller. Using sequence HVscan-125×8-15_5PreBias-DCRC2_250V-30Flash-30wait-2hrData-10minSubRun.msl CDMS detector: Driver Gains = 2x, QET biases = (280/280/305)/(140/280/295) uA, Front-End Gains = (10/10/10)/(10/15/10) NaI detector: 1.1 kV (for real) → NaI B/C (dynodes terminated) → Ortec 452(Neg input, gain=2.5, shaping = 6 us, output=+10V)/ Ortec 575A(Neg input, gain=5, shaping = 3 us) → x10/x10 attenuator → DCRCX(4) PB/PA, Driver Gains = 1/1, PhononWaveFormLength = 1024 (512 samples), PhononPrepulseSamples = 64 (64 samples) 1000 BOR randoms, trigger varies |
| 0916 | DCRC3pC railed low. Adjust driver offset from -0.5 to -1.2 |
| 0920 | Add some LN2 to the cold trap bath from the 5L dewar. LN2 Bath is probably less than half full. |
| 0923 | Large LN2 dewar is totally empty. The ebox seems to be purged well enough for now. At -125V bias, we have -10mV leakage ⇒ -121V at detector. |
| 0950 | Helium recovery meter = 229000 cuft |
| 1135 | Change trigger thresholds on DCRC3pB/C/D to 15/18/17 during pause after flash |
| 1245 | HV leakage is -10.3mV. Still hanging in there with no (or very little) purge gas flow |
| 1400 | Stop sequence during pause after flash. |
| Begin warmup | |
| 1400 | Stop circulation: close V6. Allows mix to expand into still line after 5 minutes Still pressure starts rising, > 1 mbar. Tower temperature rises above 100 mK. G1/G2 fall below 100 mbar. |
| 1410 | Pump mix from LN2 Traps to dump: Close V13b to close inlet to trap 2 (the one we are circulating through), close V1 to isolate condenser. Open V9 to open pump outlet to dump. Open V5 to pump out Trap 2. When trap is low close 12b & 5, open 12a to check Trap 1. It's essentially empty. G2(dump) = 38.2 mbar. |
| 1415 | Return Na22 source from fridge back to safe |
| 1420 | Isolate Trap 1/2 and 3He pump: close V12a/b to isolate Trap 1/2, close V5 to stop pumping on lines, close V9 to isolate 3He pump from dump. Turn off 3He pump. |
| 1420 | Open Condenser and Still to Dump: open V1, V4, V14 |
| 1420 | Change LakeShore bridge range 200 → 6.32 kΩ, leave excitation at 6.32 uV |
| 1420 | G1 (dump/fridge) = 13.4 mbar. Tower = 390 mK and rising. |
| 1430 | Main bath = 24.3% |
| 1430 | Stop 1K Pot: Close 1K Pot speedivalve to stop pumping on pot. Leaving needle valve open. Close V4a and valve to 4He pump. Open 4He outlet to “exhaust” and close recovery valve. Turn off 4He pump. |
| 1435 | G1 (dump/fridge) = 13.0 mbar. Tower/1K Pot = 0.44/2.1 K. |
| 1510 | G1 (dump/fridge) = 20.2 mbar. Tower/1K Pot = 0.53/3.4 K. |